The metabolism is at its best during mornings just when you have woken up and just before you have eaten breakfast. This means it will be easier to lose weight if you take a walk just after waking up.My suggestion is to start with 20 minutes, then increase it to 30 minutes after a couple of days.At times I take walks, or powerwalks, right after waking up. It really wakes me up and gives me energy, especially now when it's winter here up north...I think it's a good way to start the day, if not the perfect way!